1. Field of the Invention
The present invention relates to an improvement in an engine starting apparatus started by a self-starter mechanism.
2. Description of the Related Art
There exists a variety of engine starting apparatuses wherein a crankshaft is started by a self-starter mechanism accommodated in a case. Such an engine starting apparatus is disclosed, for example, in Japanese Utility Model Post-Exam Publication No. HEI-6-23739 and Japanese Patent Laid-Open Publication No. HEI-2-108854.
The engine starting apparatus disclosed in Japanese Utility Model Post-Exam Publication No. HEI-6-23739 includes a plurality of supports provided on an outer periphery of an intake aperture formed in a fan cover for covering a cooling fan mounted on a crankshaft of an engine, a cover member attached to ends of the supports, and a self starter connected to the cover member through plural screws such that the crankshaft is connected to an output side of the self starter. A starter motor of the self starter is disposed outside the plural supports. Upon rotation of the cooling fan, external air is taken into gaps between the plural supports to enter into the fan cover through the intake ports, thereby cooling the engine. Further, the engine starting apparatus is designed such that the self starter motor is turned 180 degrees on the engine after the plural screws are removed to detach the self starter from the engine.
However, the starter motor of the aforementioned engine starting apparatus is disposed outside the plural supports in parallel thereto and further protrudes toward the engine. Therefore, when the engine starting apparatus is turned on the engine, the engine and the starter motor bump against each other to thereby limit attachment of the engine starting apparatus to the engine. Consequently, there is a demand for an improvement to prevent the starter motor from bumping against the engine.
An engine starting apparatus disclosed in Japanese Patent Laid-Open Publication No. HEI-2-108854 includes a recoil starter case formed integrally with a starter motor case, a battery case assembled with the former to provide a case unit, and a fan case forming therein an intake port having an outer periphery attached to the case unit through four bolts. The starter motor is disposed oppositely from the engine in parallel to a side wall of the recoil starter case.
In the engine starting apparatus thus arranged, a large number of slit-shaped external air intake apertures for taking external air thereinto are formed in the side wall of the recoil starter case. Upon rotation of a cooling fan mounted on a crankshaft, external air is taken into the fan case through the external air intake apertures formed in the side wall of the recoil starter case to thereby cool an engine body.
However, since the starter motor and the battery case of the engine starting apparatus are mounted on a peripheral portion of the recoil starter case in juxtaposition, the external air intake apertures can not be formed thereat. Thus, it becomes impossible to take in external air throughout the entire periphery of the recoil starter case, thereby making flow of external air taken into the fan case non-uniform. Therefore, the engine body is not cooled uniformly. Consequently, there is room for improvement to enhance performance for cooling the engine body. Further, partial disposition of the external air intake apertures makes it difficult to increase total cross-sectional area of the plural external air intake apertures. Furthermore, provision of the small total cross-sectional area exerts influence on cooling ability of the engine starting apparatus for the engine body. Accordingly, there is room for improvement to increase the total cross-sectional area.
Moreover, in the aforementioned engine starting apparatus, the crankshaft is rotated by starting the starter motor. Otherwise, by pulling a lever by hand to unwind a starting rope, a starter wheel is rotated to thereby rotate the crankshaft. However, upon pulling the starting rope, a large pulling force acts on the vicinity of a starting rope pulling port of the recoil starter case. Although the recoil starter case is therefore required to be rigid to withstand the large pulling force, it is also considered that the number of bolts for mounting the recoil starter case to the engine body are increased instead of improving the rigidity of the recoil starter case. However, the increase in the number of bolts not only increases the number of parts corresponding thereto but also invites difficulty in mounting the recoil starter case to the engine body. Moreover, in the case where the starter motor is disposed in close proximity to the starting rope pulling port, the starter motor presents an obstruction to an operation of pulling the starting rope. Therefore, there is room for improvement in disposition of the rope pulling port and the starter motor.
Further, in Japanese Utility Model Laid-Open Publication SHO-63-100674, there is disclosed an engine starting apparatus including a pinion gear and an output shaft of a starter motor both accommodated in a magneto chamber adjacent to a crankcase of an engine body, and a recoil starter mechanism accommodated in a recoil chamber adjacent to the magneto chamber. Although a recoil reel of the recoil starter mechanism is disposed coaxially with the pinion gear, a partition wall separates the magneto chamber accommodating therein the pinion gear from the recoil chamber accommodating therein the recoil reel of the recoil starter mechanism. The engine starting apparatus is arranged such that a crankshaft is rotated by either the starter motor or a recoil starter by means of the pinion gear and a magneto device meshing with the pinion gear.
The foregoing engine starting apparatus has the pinion gear and the recoil starter, which are accommodated in the respective chambers in the manner as stated above. It is therefore unlikely that lubricating oil clung to the teeth of the pinion gear is scattered to dirty a starting rope of the recoil starter and that the starting rope is engaged with the teeth of the pinion gear. However, since there are provided the two chambers, the engine starting apparatus undesirably becomes complicated in construction and large in size. Thus, there is room for improvement to provide a simply arranged and small-sized engine starting apparatus.
Moreover, the applicants of the present invention have proposed an engine starting apparatus having a starter motor and a recoil starter in Japanese Patent Laid-Open Publication No. HEI-3-258969.
The proposed engine starting apparatus includes a first one-way clutch provided at one part of a series of decelerating gears for decelerating rotation of the starter motor, and a pulley disposed between a final gear of the series of decelerating gears and a crankshaft of an engine so that the rotation of the starter motor is transmitted to the crankshaft through centrifugal ratchets provided at the pulley and the series of decelerating gears. On a supporting shaft of the final gear, there is provided a clutch plate meshed with the centrifugal ratchets. A release cam is provided outwardly of the clutch plate. A second one-way clutch is forced into an inner diameter portion of the release cam.
In the engine starting apparatus as described above, when the clutch plate is rotated in such a direction as to start the engine, the clutch plate and the centrifugal ratchets start to rotate in mesh with each other. On the other hand, when the clutch plate is rotated in a direction opposite to the former due to an overload on the engine under operation, the clutch plate is forcibly disengaged from the centrifugal ratchets by the release cam prevented from rotating in the opposite direction by the second one-way clutch.
However, since each of the two one-way clutches uses a well-known needle roller one-way clutch, they must be extremely precise in dimension. Further, needle rollers are partially worn by long-term use thereof to thereby make the one-way clutches inoperative often. Furthermore, since such a needle roller one-way clutch is expensive, there has been desired an improvement in the one-way clutch.